In the Second Age, Narsil was an heirloom of the descendants of Elros, the first King of Númenor. Although nothing is said of Narsil during this period, it eventually came into the hands of Elendil, a distant descendant, towards the close of the Second Age.

Elendil used Narsil in the Siege of Barad-dûr, but Sauron killed Elendil and the sword broke into two pieces under him as he fell. Elendil's son Isildur took up the sword and used its shard to cut the One Ring from the hand of Sauron. Isildur took the shards home with him. Shortly before Isildur was killed in the second year of the Third Age in the Disaster of the Gladden Fields, the shards were rescued by Ohtar, squire of Isildur's oldest son. He took them to Rivendell, where Isildur's youngest son Valandil was fostered.

In Third Age 3019 Narsil was reforged in Rivendell as Andúril, the "Flame of the West", for Aragorn, the heir of Isildur. He carried the sword during his journey south as part of the Fellowship of the Ring, and it featured prominently at several points in the story, where it was sometimes referred to as the "Sword That Was Broken" or "The Sword Reforged".

Portrayal in Adaptations

Narsil was not broken in two but in several parts, which were kept at Rivendell, and by Sauron stepping on it instead of it breaking as Elendil fell. The sword is not reforged into Andúril until the third film, when Arwen persuades Elrond to have Elven smiths reforge it from the shards and bring to Aragorn.

In the books, he actually wears the broken blade and shows it to the Hobbits when they meet at the Prancing Pony in Bree, and its reforging prior to the departure of the Fellowship is a decisive move toward kingship.

The reforging of Narsil is experienced by the player in the quest arc called "The Blade that was Broken." The player sets out to find the last of the Silithair in order for the Elf-smiths of Imladris to reforge the sword.